By way of example, there are basically two approaches which are used to circumvent piracy of data, video or audio program material. One approach is to apply an anti copy protection signal to the program material so that a recorder, such as a video cassette recorder (VCR), will produce a generally unsatisfactory picture. The other approach is to apply a copy protection information signal or a content control signal which controls, for example, a compliant recorder, to determine whether a recording is allowed or not and, if allowed, the number of copies, the duration of copying, other conditions and or restrictions which may be applied, etc.
Content control systems such as those used in the recording, displaying and or distribution of program material, rely on various content control bits or signals to provide subsequent control command functions for restrictions on, or authorizations of, program use. Such restrictions may be for example, copy never, copy once, copy for a selected duration, copy allowed, display, transmission or distribution, allowed or not, etc.
It should be noted that a copy protection signal can serve as a copy protection information signal for a record and or a content control system. In some cases, at least a portion of a copy protection signal, for example, pseudo sync and or automatic gain control (AGC) pulses, is sensed by a recorder or other compliant device, and “permission” to record, not record or provide some other function, is then dictated. In some cases a weakened, modified or derived copy protection signal, or portions thereof, which may have a reduced copy protection effect, may be used for content control or management.
On the other hand, not all copy protection information signals may serve as a copy protection signal. There are some copy protection information signals that are in the form of standard data or test signals in the vertical blanking interval. One such data signal is a copy generation management system (CGMS) signal which may comprise a series of positive-going pulses generally located in the vertical blanking interval (VBI) or overscan region. These data signals do not affect non-compliant recorders such as an off the shelf consumer VCR or VHS recorder. However, these data signals will affect a compliant recorder specifically made to receive and interpret the data or copy protection information signal and which then can provide a control command which may be used to effect selected copy protection conditions or other functions.
By way of further example, a content control system may use, as control commands, copy protection signals such as color burst phase modifications (CS), automatic gain control pulses (AGC), and or pseudo sync pulses (PS). Depending on the properties or combinations of any of these copy protection signals, a content control system is established with various properties. As a simple example, one can define the following:
a) If AGC pulses are off and CS is off, then copying or distributing is allowed.
b) If AGC pulses are on and CS is off, then copying or distributing is allowed for a duration.
c) If AGC pulses are on and CS is on, then recording or distributing is not allowed.
In the case of the color burst phase modifications (termed “color stripe” or CS), the signals to be detected can be for example of a 2 line or 4 line type, meaning there are color stripe signals in two lines out of m lines or in four lines out of m lines. In this situation, a 2 line CS copy protection signal may form one control command while a 4 line CS copy protection signal may form a different control command.
A content control system includes a compliant device adapted to receive signals and interpret these signals as control commands such as illustrated above. For example, a compliant device may be a personal video recorder (e.g., personal video recorder [PVR], Tivo, or RePlay recorder, trademarks of Tivo inc. and D&M Holdings, Inc. respectively), a digital videodisc recorder (e.g., digital video disc [DVD] recorder), a video to digital translator unit such as a video to USB or IEEE1394 adapter, a video to wireless transmitter (e.g., video to WiFi or the like), etc.
It is to be understood that a compliant device is a device which includes reader or detection circuitry which is designed to recognize particular signals, that is, which interprets the signals (pulses), and provides a corresponding control, that is, a control command, based on the particular signals. For example, a reader may receive information via analog or digital signals or embedded signals. After information is received, a “judgement” or “interpretation” (e.g., command) is made by a content or record control system. A reader may be implemented in any combination of an analog circuit, a digital circuit, and or software. In many instances, a reader relies on reference signals to locate a content control signal or a data signal, which provides information to a content control or record control system. In another instance, the information signal may be embedded into the program content. One such example of embedding is using a watermark waveform or signal added or inserted to a program signal such as a video or an audio or a digital signal. In an example with an embedded signal, a reader then would retrieve information from a watermark for (e.g., producing a command to) a content control or record control system.
An example of a content control system is disclosed in a (copending) U.S. patent application Ser. No. 10/753,844, filed Jan. 7, 2004, to Mark A. Hollar, entitled METHOD AND APPARATUS FOR CONVEYING RIGHTS ACROSS AN ANALOG VIDEO INTERFACE, and assigned to the same assignee as this application, and which is incorporated herein by reference. Another example of a content control system is disclosed in a (copending) U.S. Patent application Ser. No. 60/623,297 filed Oct. 28, 2004 to Ronald Quan, entitled CONTENT MANAGEMENT FOR HIGH DEFINITION TELEVISION, and assigned to the same assignee as this application, and which is incorporated herein by reference.